The Primary Breast Cancer Therapy Group (NSABP) is conducting two protocols. The first, evaluating the efficacy of total (simple) mastectomy with and without radiation and radical mastectomy was begun in August, 1971. More than 950 patients have been entered from 34 institutions by more than 250 surgeons. Initially, patients are judged clinically to have negative or positive axillary nodes and randomized accordingly. The clinically negative axillary node patients are assigned to radical mastectomy, total (simple) mastectomy with postoperative radiation, or total (simple) mastectomy alone. The clinically positive axillary node patients are assigned to radical mastectomy or total (simple) mastectomy with pgstoperative radiation. It is premature to make statements relative to efficacy of the different treatment modalities. It has, however, been demonstrated that patients randomized into the various treatment categories are similar according to a variety of criteria. Information has also been obtained relative to the pathology of the tumors and complications of the various treatments. Submission of data is satisfactory. A second study evaluating the efficacy of prolonged chemotherapy as an adjunct to mastectomy utilizing L-phenylalanine mustard was begun mid-October, 1972. Twenty-six institutions are contributing patients to this protocol. Data is not sufficient to make any statement relative to results.